Unlike the traditional radio systems, wireless communication between the various electronic devices or blocks of one electronic system, i.e. the transmission of analog and digital signals at close—millimeter or centimeter—distances, can be implemented effectively by means of the capacitive coupling. Recently, the capacitive coupling devices have become more widespread due to the appearance of new element base of electronic components, which become more high-speed and are more suitable for making electrical circuits for wireless capacitive coupling devices on practice.
Capacitive coupling systems are known as such systems in which the signals are transmitted from one conductive element to another conductive element, provided that two conductors are separated by a nonconductor. An electric field is created between two conductors, and as a result, an electrical potential applied to the first conductor can be detected on the second conductor through the electric field.
Capacitive communication systems exist as a whole, including the ones where data is transmitted between integral circuits. For example, the U.S. Pat. No. 6,916,719 (published on Jul. 12, 2005) describes apparatuses and methods, which comprise “pairs of half-capacitor plates”, with one half located on each chip, and a module or a substrate are used to couple signals capacitively from one chip, module or substrate to another. A disadvantage of these systems is that they usually require a common source of power supply and grounding and also the lack of compensation of distortion that may result, in certain cases, to narrowing of operating frequency range and to errors in the data.
The U.S. Pat. No. 6,336,031 (published on Jan. 1, 2002) describes (I) a transmitter that comprises a pair of electrodes separated in space, and a transmit circuitry for varying the voltage difference applied across the transmitter's electrodes in order to vary the spatial gradient of the electric potential field generated by the transmitter in accordance with the data to be transmitted and (II) which comprises a pair of electrodes separated in space and a receive circuitry which detects these variations in the quasi-electrostatic potential field in order to receive the transmitted data.
Another capacitive communication system, described in claim for an invention US 2009/0143009A1 (published on Jan. 4, 2009), describes a signal transmitting apparatus having a signal transmitting electrode, which receives transmitted signal, and a signal receiving apparatus having a signal receiving electrode, from which the signal is carried out and converted, including a comparator with a hysteresis characteristic, with the aim to receive the transmitted data. The drawback of the above inventions is the absence of compensation of distortion in capacitive communication channel which may result in errors in the data when transmitting two or several rows of ones and zeros in a dataflow.
A significant drawback of systems, methods and devices described in these patents is that they do not solve the task of minimizing the impact of external factors (such as electromagnetic interference, resulting in the higher number of errors in a channel and/or the actual loss of connection) on the capacitive connector and thus on the system operation.
The methods of signal compensation for the implementation of a wireless transmission and receiving of signals, which may include signal filtering, where the correction occurs on both sides of the capacitive transmission system, are also known. But the use of filtering in a filtering transmitting apparatus results not only in the partial signal precompensation but, simultaneously, in the partial signal distortion, which in case of unstable capacitive connection parameters (for example, between devices) also can lead to the changes in transmission efficiency depending on the data signals being transmitted.
Given the existence of these technologies, there is still a need for improved systems, methods and apparatuses of wireless communication that can ensure high speed data transmission, with the lower level of errors during transmission, in the presence of electromagnetic interference, and which do not require common wires or grounding, do not need much power, including operation in case of wireless power supply.